A preparation method of Dendrobium officinale polysaccharide extract

Abstract

The present invention discloses a method for preparing a polysaccharide extract of Dendrobium officinale. The specific steps include: after the Dendrobium officinale is roughly crushed, it is firstly extracted with water, filtered and separated, extracted 1 to 3 times, the drug residue collected after filtration is crushed and then extracted with water for the second time, centrifuged and separated, extracted 1 to 2 times, and the centrifuge liquid is collected; then dried to obtain a polysaccharide extract B of Dendrobium officinale; the polysaccharide extract B of Dendrobium officinale is an extract containing polysaccharides with a molecular weight of 1.5 million to 2.5 million. The method of the present invention solves the technical defects of the existing water extraction technology, realizes the simultaneous extraction of polysaccharides of Dendrobium officinale with different molecular weights, solves the technical defects of difficult extraction of fine powder and high energy consumption, and also solves the technical defect of low extraction rate of coarse powder. The method of the present invention is simple to operate, easy to be applied in industrial production, and has a very high market application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of plant component extraction, and particularly relates to a method for preparing a Dendrobium officinale polysaccharide extract. Technical Background

[0002] Dendrobium officinale is an herbaceous plant of the genus Dendrobium in the Orchidaceae family. As a traditional rare medicinal material in my country, it is listed as the "first of the nine immortal herbs in China". Modern clinical applications and pharmacological studies have confirmed that Dendrobium officinale has magical effects such as nourishing yin and moistening the lungs, nourishing the stomach and promoting fluid production, and strengthening the brain and improving eyesight.

[0003] At present, there are many reports on the main chemical components of Dendrobium candidum in the literature, and the most common research is on Dendrobium candidum polysaccharides. Polysaccharides are an important type of substance in organisms and are natural high-molecular compounds formed by the polymerization of monosaccharides. Studies have shown that Dendrobium polysaccharides have the effects of improving immunity, lowering blood sugar, and anti-tumor. my country's research on polysaccharides started late, starting in the 1970s, but it has developed rapidly and has become a new hotspot in modern pharmacology research. There are many methods for extracting Dendrobium candidum polysaccharides, such as enzyme extraction, alcohol extraction, water extraction, etc. Among them, water extraction is simple to operate, has low condition requirements, low cost, and does not introduce other substances. It is the most economical and safe extraction method.

[0004] The preparation method of Dendrobium officinale polysaccharide water extraction is generally: crush the Dendrobium officinale medicinal material, add water to extract, filter the extract and concentrate it, and finally dry the concentrate. The first water extraction method of Dendrobium officinale polysaccharide is: crush the Dendrobium officinale medicinal material into fine powder, add water to extract, and extract according to the conventional amount of water added. The fine powder of Dendrobium officinale will absorb water and heat into a paste during the water extraction process, and it cannot be effectively extracted. If the amount of water added is increased, the solid-liquid ratio will be large, the extraction efficiency is not high, which is not conducive to industrial production, and the high amount of water added will also lead to increased energy consumption for extraction, concentration, and drying, resulting in energy waste. The second extraction method of Dendrobium officinale polysaccharide is: use coarse powder for extraction. The coarse powder extraction will not appear in a paste state, but the use of coarse powder for extraction also has the following problems: the polysaccharide yield is not high and high molecular weight polysaccharides cannot be effectively obtained. This is because the solid particles of the coarse powder are too large, and the macromolecular polysaccharide molecules in the coarse powder cannot be precipitated during water extraction.

[0005] Patent application CN201711480845.5 discloses a process for extracting Dendrobium officinale polysaccharides. Through the steps of washing, pressing, crushing, freezing-thawing, water extraction, filtering, and concentration, crude Dendrobium officinale polysaccharides and pure Dendrobium officinale polysaccharides are obtained. The process uses crushing technology, multiple freezing-thawing technology, organic solvent reflux degreasing technology, water extraction technology, etc. to obtain a crude Dendrobium officinale polysaccharide with a yield of about 16% and a content of about 66%. The process has complex production steps, uses freezing-thawing technology multiple times, has high energy consumption, and the content and yield of crude Dendrobium officinale polysaccharides are not high.

[0006] At the same time, the properties and functions of polysaccharides of different molecular weights are different. There is currently no report on the industrial separation and extraction of polysaccharides from Dendrobium officinale according to molecular weight.

[0007] Therefore, it is necessary to explore a method for efficiently extracting polysaccharides of different molecular weights from Dendrobium officinale. Summary of the invention

[0008] In order to overcome the deficiencies of the prior art, the present invention aims to provide a method for efficiently extracting polysaccharide extracts of Dendrobium officinale with different molecular weights.

[0009] In order to achieve the above object, the present invention adopts the following technical solution:

[0010] A method for preparing a polysaccharide extract of Dendrobium officinale, comprising the steps of extraction, drying, etc., and the specific steps include:

[0011] After the Dendrobium officinale is roughly crushed, the extract is firstly extracted with water, filtered and separated, and extracted 1 to 3 times, the residue collected after filtration is crushed and then extracted with water for the second time, centrifuged and separated, extracted 1 to 2 times, and the centrifuge liquid is collected; and then dried to obtain the Dendrobium officinale polysaccharide extract b;

[0012] The Dendrobium officinale polysaccharide extract B is an extract containing at least 81.8wt% of polysaccharides with a molecular weight of 1.5 million to 2.5 million.

[0013] As a preferred embodiment, the coarsely crushed Dendrobium officinale has a particle size of 1 mm to 25 mm.

[0014] As a preferred embodiment, the conditions of the first water extraction and the second water extraction are extraction in water at 80-100°C for 1-2 hours;

[0015] As a preferred solution, the centrifugal conditions are: 4000 rpm, time 10 to 15 min.

[0016] As a more optimal solution, the drying conditions are: vacuum drying at 50-70°C.

[0017] As a more optimal solution, the Dendrobium officinale polysaccharide extract b is an extract containing at least 81.8wt% of polysaccharides with a molecular weight of 1.5 million to 2.5 million.

[0018] As a preferred embodiment, after the centrifuge liquid is collected, alcohol precipitation is performed to obtain a precipitate, and then the precipitate is dried to obtain the Dendrobium officinale polysaccharide extract b.

[0019] As a more optimal solution, the alcohol precipitation conditions are: adding more than 90 vol % of alcohol to the centrifuge until the alcohol concentration of the supernatant reaches 50 vol % to 85 vol %, standing for 8h to 24h, collecting the precipitate, and adding more than 90 vol % of alcohol to the precipitate to remove the remaining water to obtain a precipitate.

[0020] As a more optimal solution, after collecting the centrifuge liquid, it is concentrated and then precipitated with alcohol to obtain a precipitate, and then the precipitate is dried to obtain the Dendrobium officinale polysaccharide extract b. The concentration is concentrated to a concentrated liquid with a soluble solid content of 2 wt% to 5wt% under the conditions of 65°C to 75°C and a vacuum degree of 0.06 Mpa to 0.1 Mpa.

[0021] As a preferred embodiment, the alcohol is ethanol.

[0022] As a preferred embodiment, after the first water extraction, the extract is collected, the extract is centrifuged to obtain a centrifuge, and then the centrifuge is dried to obtain a Dendrobium officinale polysaccharide extract a; the Dendrobium officinale polysaccharide extract a is an extract containing at least 25wt% of polysaccharides with a molecular weight of 500 to 300,000.

[0023] As a more optimal solution, after the first water extraction, the extract is collected, the extract is centrifuged to obtain a centrifuge, and the centrifuge is concentrated and dried to obtain a Dendrobium officinale polysaccharide extract a; the concentration is concentrated to a concentrate with a soluble solid content of 2 wt% to 5wt% under the conditions of 65°C to 75°C and a vacuum degree of 0.06 Mpa to 0.1 Mpa.

[0024] The preparation method of the Dendrobium officinale polysaccharide of the present invention is that the medicinal materials are cut into sections first, low molecular weight polysaccharides are extracted, and then the medicinal residues are crushed again and extracted again, so that polysaccharide extracts with different molecular weights can be prepared, and high-purity (purity is as high as 80% or more) high molecular weight Dendrobium officinale polysaccharide extracts are also prepared, and the yield of Dendrobium officinale polysaccharides with a molecular weight of 500 to 300000 can also reach more than 20%. The method of the present invention fills the technical gap that the prior art cannot produce Dendrobium officinale polysaccharide products with different molecular weight gradients in large quantities, and the method of the present invention is simple and easy to operate and is convenient for industrial production.

[0025] The preparation method of the present invention adopts the steps of water extraction, alcohol precipitation and the like, which avoids the introduction of new substances in the extraction of plant polysaccharides to the greatest extent possible and ensures that the extract does not contain other impurities.

[0026] Existing studies have shown that the biological activity of plant polysaccharides is closely related to their molecular weight. Bao Suhua et al. reported (Study on the Antioxidant Activity of Dendrobium Officinale Polysaccharides with Different Molecular Weights in Vitro [J]. Food Science, 2009, 30(21): 123-127) that Dendrobium Officinale polysaccharides with different molecular weights have different scavenging effects on different free radicals. Polysaccharides with different molecular weights can be used to scaveng different free radicals. They can also be applied to different fields according to their high and low molecular weights. For example, low molecular weight polysaccharides are easily absorbed through the skin and can be applied to the cosmetics field. High molecular weight polysaccharides have a better lipid-lowering effect because their molecular weight increases and their viscosity increases, so they can be applied to the food field.

[0027] The method of the present invention solves the technical defects of the existing water extraction technology, realizes the simultaneous extraction of Dendrobium officinale polysaccharides with different molecular weights, solves the technical defects of difficult extraction of fine powder and high energy consumption, and also solves the technical defect of low extraction rate of coarse powder, so it has good technical advantages; the method of the present invention is simple to operate, easy to apply in industrial production, and has a very high market application prospect. DETAILED DESCRIPTION

[0028] In order to make the present disclosure more easily understood, certain terms are defined herein. Additional definitions are set forth in the detailed description.

[0029] The term "wt%" used herein means percentage by mass.

[0030] The term "vol%" used herein means volume percentage.

[0031] The polysaccharide content detection method in this article is based on the detection of polysaccharides under Dendrobium officinale in Part I of the 2015 edition of the Pharmacopoeia of the People's Republic of China; the polysaccharide molecular weight distribution is detected by high-performance gel filtration chromatography, and this test is entrusted to the Analysis and Testing Center of Jiangnan University.

[0032] Example 1 Preparation of Dendrobium officinale polysaccharide extract

[0033] Extraction: Take 350g of dry strips of Dendrobium candidum (purchased from Anguo Yifang Pharmaceutical Co., Ltd.), chop them into coarse powder with a particle size of 1mm to 25mm, put them in a container, add 3500g of water in turn, extract once at 100℃, extract for 2h, collect the extract a and the residue through a net, crush the residue and add 20 times the mass of water to extract twice, each time for 2h, to obtain the extract b; centrifuge the extract a and b at 4000 rpm for 10min, respectively, to obtain centrifuge a and b; concentrate the centrifuge a and b at 70℃ and vacuum degree of 0.06 Mpa to a soluble solid content of 2wt%, to obtain concentrate a and concentrate b; add 95 vol% ethanol to the concentrate b, let it stand overnight, filter the filtrate to recover the ethanol to obtain the precipitate b, and then wash the precipitate b with 95 vol% ethanol 2 to 5 times to remove most of the water in the precipitate b; the concentrated solution a and the precipitate b are vacuum dried at 60°C to obtain 30g of Dendrobium officinale polysaccharide extract a and 80g of Dendrobium officinale polysaccharide extract b.

[0034] After testing, the polysaccharide content of Dendrobium officinale polysaccharide extract a was 30.5wt%, and the polysaccharide molecular weight distribution was 500-300000; the polysaccharide content of Dendrobium officinale polysaccharide extract b was measured to be 92.8wt%, and the polysaccharide molecular weight distribution was 1.5 million-2.5 million.

[0035] Example 2 Preparation of Dendrobium officinale polysaccharide extract

[0036] Extraction: Take 350g of dry strips of Dendrobium candidum (purchased from Anguo Yifang Pharmaceutical Co., Ltd.), chop them into coarse powder with a particle size of 1mm-25mm, put them in a container, add 4900g of water in turn, extract twice at 90℃, each time for 2h, collect the extract a and the residue through a sieve, crush the residue and add 15 times the weight of water to extract once, each time for 2h to obtain the extract b; centrifuge the extracts a and b at 4000 rpm for 15min, respectively, to obtain centrifuges a and b; concentrate the centrifuge a at 65℃ and vacuum degree of 0.1Mpa to a concentrate a with a soluble solid content of 5wt%; add 90 vol % ethanol, let it stand overnight, filter the filtrate to recover ethanol to obtain precipitate b; the concentrated solution a and precipitate b were vacuum dried at 50°C to obtain 28g of Dendrobium officinale polysaccharide extract a and 69.9g of Dendrobium polysaccharide extract b.

[0037] After testing, the polysaccharide content of Dendrobium officinale polysaccharide extract a was 25wt%, and the polysaccharide molecular weight distribution was 500-300000; the polysaccharide content of Dendrobium officinale polysaccharide extract b was measured to be 81.8wt%, and the polysaccharide molecular weight distribution was 1.5 million-2.5 million.

[0038] Example 3 Preparation of Dendrobium officinale polysaccharide extract

[0039] Extraction: Take 100g of dry strips of Dendrobium candidum (purchased from Anguo Yifang Pharmaceutical Co., Ltd.), chop them into coarse powder with a particle size of 1mm-25mm, put them in a container, add 800g of water in turn, extract twice at 80℃, each time for 2h, collect the extract a and the residue through a sieve, crush the residue and add 10 times the weight of water to extract twice, each time for 1h, to obtain the extract b; centrifuge the extract a and b at 4000 rpm for 10min, respectively, to obtain the centrifuge a and b; concentrate the centrifuge a and b at 75℃ and vacuum degree of 0.08 Mpa to a soluble solid content of 3wt%, to obtain the concentrate a and the concentrate b; add 95 vol % ethanol, let it stand overnight, filter the filtrate to recover ethanol to obtain precipitate b; the concentrated solution a and precipitate b were vacuum dried at 70°C to obtain 9.2g of Dendrobium officinale polysaccharide extract a and 28.1g of Dendrobium polysaccharide extract b.

[0040] After testing, the polysaccharide content of Dendrobium officinale polysaccharide extract a was 32.4wt%, and the polysaccharide molecular weight distribution was 500-300000; the polysaccharide content of Dendrobium officinale polysaccharide extract b was measured to be 90.4wt%, and the polysaccharide molecular weight distribution was 1.5 million-2.5 million.

[0041] The above examples are only a few specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and there are many variations. All variations that can be directly derived or associated with the content disclosed by ordinary technicians in this field are considered to be within the protection scope of the present invention.

Claims

1. A method for preparing a polysaccharide extract of Dendrobium officinale, comprising extraction and drying steps, characterized in that: The specific steps are: After the dried strips of Dendrobium officinale are roughly crushed, the first water extraction is carried out, and the extraction is carried out by filtering and separating, and the extraction is carried out 1 to 3 times. After the residues collected after filtering are crushed, the second water extraction is carried out, and the centrifugal separation is carried out, and the extraction is carried out 1 to 2 times, and the centrifugal liquid is collected; the centrifugal liquid is precipitated with alcohol to obtain a precipitate, and then dried to obtain the Dendrobium officinale polysaccharide extract b; or, the centrifugal liquid is concentrated, precipitated with alcohol to obtain a precipitate, and then dried to obtain the Dendrobium officinale polysaccharide extract b; the Dendrobium officinale polysaccharide extract b is an extract containing at least 81.8wt% of polysaccharides with a molecular weight of 1.5 million to 2.5 million; After the first water extraction, the extract is collected, the extract is centrifuged to obtain a centrifuge, and then the centrifuge is concentrated and dried to obtain a Dendrobium officinale polysaccharide extract a; the Dendrobium officinale polysaccharide extract a is an extract containing at least 25wt% of polysaccharides with a molecular weight of 500-300,000; the coarsely crushed particle size of the Dendrobium officinale dried strips is 1mm-25mm; the conditions for the first water extraction and the second water extraction are extraction in water at 80-100°C for 1-2 hours; The concentration is concentrated at 65° C. to 75° C. and a vacuum degree of 0.06Mpa to 0.1Mpa to a concentrated liquid having a soluble solid content of 2wt% to 5wt%.

2. The preparation method according to claim 1, characterized in that: The centrifugal conditions are: 4000 rpm, time 10 to 15 min.

3. The preparation method according to claim 1, characterized in that: The drying conditions are: vacuum drying at 50-70°C.